Django requests: number of instances with FK instance for model

Question

It should be easy, but for some reason, it's hard for me to find it. I have the following:

App(models.Model):
    ...

Release(models.Model):
    date = models.DateTimeField()
    App = models.ForeignKey(App)
    ...

How can I execute a query for all application objects that have at least one version?

I started typing:

App.objects.all().annotate(release_count=Count('??????')).filter(release_count__gt=0)

That will not work because the graph does not cover the relationship, at least as far as I can tell.

BONUS:

Ultimately, I would also like to be able to sort applications by the latest release date. I am thinking of caching the latest release date in the application to make it a little easier (and cheaper) and update it in the Release model method save, unless of course there is a better way.

Edit:

I am using Django 1.1 - do not mind switching to dev in anticipation of 1.2 if there is a good reason.

Answer 1

:

App.objects.annotate(release_count=Count('release')).filter(release_count__gt=0)\
    .order_by('-release__date')

Answer 2

App.objects \
    .annotate(release_count=Count('release')) \
    .(release_count__gt=0) \
    .order_by('-release_count')

. .